Method for Operating a Projectile Loom

ABSTRACT

It is the object of the invention to avoid weaving defects, which due to a starting process of a projectile weaving machine in fabrics, especially such with ground weaves, as a cause of the starting process. The object is achieved according to the invention in that the projectile weaving machine is operated in the slow speed running after each starting process during the first weaving cycle, in that during the slow speed running the weft thread is inserted with a velocity adequate for the prescribed operating rotational speed, and in that the projectile weaving machine is operated with the prescribed operating rotational speed directly after the end of the first weaving cycle.

The invention relates to a method for operating a projectile loom, whereby during a weaving cycle at least one weft thread is inserted into a loom shed formed of warp threads, after its insertion the weft thread is held clamped on the inlet and outlet side of the loom shed and is cut to length, and thereafter the weft thread in the clamped held condition is beat-up against the beat-up edge of a woven web or fabric to be produced and bound by the warp threads.

In the operation of projectile weaving machines for the production of woven webs or fabrics, especially fabrics with ground, base or plain weaves, for example fabrics with twill weave, fabrics with plain or tabby weave, and fabrics with satin weave, weaving defects often arise as a result of a starting process of the weaving machine. The cause of such start processes in the most cases are weft or warp thread breaks or machine stoppages necessitated by the weaving technology.

It is the object of the invention to avoid weaving defects, which due to a starting process of a projectile weaving machine in fabrics, especially those with ground weaves, as a cause of a starting process of the projectile weaving machine.

The object is achieved according to the invention in a method whereby the projectile weaving machine is operated in the slow speed running after each starting process during the first weaving cycle, whereby during the slow speed running of the projectile weaving machine the weft thread is inserted with a velocity that is adequate for the prescribed operating rotational speed, and whereby the projectile weaving machine is operated with the prescribed operating rotational speed directly after the end of the first weaving cycle. The term weaving cycle is here understood to mean the time duration between two successive beat-ups of the weaving reed against the beat-up edge of the woven web or fabric to be produced. In that regard, the weft thread insertion occurs at a rotational speed of the main drive shaft of the projectile weaving machine of less than 200 min⁻¹, preferably at a rotational speed between 40 min⁻¹ and 100 min⁻¹.

In further embodiment of the invention, the projectile weaving machine is operated in such a manner that a transition from the slow speed running rotational speed to the prescribed operating rotational speed is carried out directly after the beating-up of the inserted weft thread against the beat-up edge of the fabric. Furthermore it is provided according to the invention, that the work or process steps following each staring process of the projectile weaving machine, namely slow speed running during the first weaving cycle after the starting process, insertion of the weft thread during the slow speed running of the projectile weaving machine, and operating the projectile weaving machine in a prescribed operating rotational speed, are carried out automatically.

With the inventive method, the weaving defects typically arising in the starting process of the projectile weaving machine, in the manner of a start-up mark, such as so-called step formation for example, which become optically apparent especially after the finishing of the fabric, are avoided.

The invention will be explained in more detail in the following in connection with an example embodiment.

The means necessary for the production of a woven web or fabric on a projectile weaving machine are schematically illustrated in the accompanying drawing.

The warp threads 1, 2 are pulled through lamellae 3 of a weaving reed 4 and thereby form a loom shed 5. A projectile 6 carries or inserts a weft thread 7 into the opened loom shed 5. In that regard, the projectile is guided by a plurality of guide means 9 arranged on the loom slay 8, whereby the weaving reed 5 is located in its rear end position during the weft thread insertion. The weft thread 7 inserted into the loom shed 5 is held by a weft thread clamp 10 arranged on the inlet and outlet side of the loom shed 5, before it is cut off by a weft thread scissors or cutter that is arranged on the inlet and outlet side of the loom shed 5 but is not illustrated. The weft thread 7 that is thusly brought to the insertion length is beat-up against the beat-up edge 11 a of the woven web or fabric 11 in the clamped held condition, and particularly according to the present inventive solution at a slow speed running of the projectile weaving machine during the first weaving cycle after a starting process, in which slow speed running the motion of the weaving reed 4 or the slay of the weaving machine carrying the weaving reed 4 is taken into account. After completed beating-up of the weft thread 7 the projectile weaving machine automatically starts in a prescribed operating rotational speed, which generally is maintained until a stoppage of the weaving process that becomes necessary for example due to a weft thread break. After the removal or correction of the exemplary mentioned weft thread break, a renewed starting process in the sense of the method of proceeding as claimed in the patent claim 1 occurs preferably automatically. 

1. Method for operating a projectile weaving machine, whereby during a weaving cycle at least one weft thread is inserted into a loom shed formed of warp threads, thereupon the inserted weft thread is held clamped at the inlet and outlet side of the loom shed and is cut to length, and thereafter the weft thread in the clamped held condition is beat-up against the beat-up edge of a woven fabric to be produced and bound by the warp threads, characterized in that the projectile weaving machine is operated in the slow speed running after a starting process during the first weaving cycle, in that during the slow speed running the weft thread is inserted with a velocity adequate for the prescribed operating rotational speed, and in that the projectile weaving machine is operated with the prescribed operating rotational speed directly after the end of the first weaving cycle.
 2. Method according to claim 1, characterized in that the weft thread insertion occurs at a rotational speed of the main drive shaft of the projectile weaving machine of less than 200 min⁻¹, preferably between 40 min⁻¹ and 100 min⁻¹.
 3. Method according to claim 1, characterized in that a transition from the slow speed running rotational speed to the operating rotational speed occurs directly after the beating-up of the inserted weft thread.
 4. Method according to claim 1, characterized in that the process steps following each starting process of the projectile weaving machine are carried out automatically. 